From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Hansen Subject: Re: [PATCH] net/ipv4: Update sk_for_each_entry_offset_rcu macro to utilize rcu methods hlist_next_rcu. This fixes the warnings thrown by sparse regarding net/ipv4/udp.c on line 1974. Date: Wed, 27 Sep 2017 12:25:51 -0400 Message-ID: <20170927162551.GA85447@debian> References: <20170927005406.5935-1-devtimhansen@gmail.com> <20170926.200339.2029420994787006076.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: David Miller Return-path: Content-Disposition: inline In-Reply-To: <20170926.200339.2029420994787006076.davem@davemloft.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org > Tue, Sep 26, 2017 at 08:03:39PM -0700, David Miller wrote: > From: Tim Hansen > Date: Tue, 26 Sep 2017 20:54:05 -0400 > > > Signed-off-by: Tim Hansen > > This is a poor patch submission on many levels. > Apologies Dave, this is my first patch. I appreciate the quick review and helpful feedback. > But the main problem, is that there is no use of > sk_for_each_entry_offset_rcu() in any of my networking kernel trees. > Using the get_maintainers.pl on include/net/sock.h brings up your name and the netdev mailing list. Forgive me if I'm misunderstanding what you mean by this? > Referencing code by line number never works, you have to mention > what version of the kernel, what tree, and where in what fucntion > the problem is occurring. > I am using your tree net tree for now: git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git on HEAD. HEAD is c2cc187e53011c1c4931055984657da9085c763b for me currently on your tree. Before I was on the 4.13 tag pulled from linus' tree. The line number is indeed useless in hindsight since there are many different trees. I won't do that again. Using sparse 0.5.0 on HEAD of your net tree, I run make C=1 net/ipv4/. It throws the error: "net/ipv4/udp.c:1981:9: error: incompatible types in comparison expression (different address spaces) net/ipv4/udp.c:1981:9: error: incompatible types in comparison expression (different address spaces)" This points to the function sk_for_each_entry_offset_rcu() in __udp4_lib_mcast_deliver in net/ipv4/udp.c. Inspecting this macro in include/net/sock.h is what lead to this patch. Applying the patch silences those warnings but clearly this is -not- a proper way of fixing the error. Any guidance would be greatly appreciated. > Secondly, sk_for_each_entry_offset_rcu() is not meant to be used > in _raw() contexts. This is why it's not called > sk_for_each_entry_offset_rcu_raw(). Absolutely makes sense. I am not familar with the kernel naming standards fully yet but this is obvious in hindsight. > > The sparse warning is probably legitimate, and points to a bug. > > But nobody can tell where becuase you haven't told us what tree > and where this happens. Hopefully my reply has enough detail for reproduction and further debugging. Please let me know if I should supply any additional information.